Patch "s390/smp,mcck: fix early IPI handling" has been added to the 6.6-stable tree

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This is a note to let you know that I've just added the patch titled

    s390/smp,mcck: fix early IPI handling

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-smp-mcck-fix-early-ipi-handling.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ae474616380c8f8423fc6f1467a12fed6fd80e58
Author: Heiko Carstens <hca@xxxxxxxxxxxxx>
Date:   Tue Sep 5 15:49:37 2023 +0200

    s390/smp,mcck: fix early IPI handling
    
    [ Upstream commit 4a1725281fc5b0009944b1c0e1d2c1dc311a09ec ]
    
    Both the external call as well as the emergency signal submask bits in
    control register 0 are set before any interrupt handler is registered.
    
    Change the order and first register the interrupt handler and only then
    enable the interrupts by setting the corresponding bits in control
    register 0.
    
    This prevents that the second part of the machine check handler for
    early machine check handling is not executed: the machine check handler
    sends an IPI to the CPU it runs on. If the corresponding interrupts are
    enabled, but no interrupt handler is present, the interrupt is ignored.
    
    Reviewed-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
    Acked-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
    Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
    Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 442ce0489e1a1..3a54733e4fc65 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -258,15 +258,9 @@ static inline void save_vector_registers(void)
 #endif
 }
 
-static inline void setup_control_registers(void)
+static inline void setup_low_address_protection(void)
 {
-	unsigned long reg;
-
-	__ctl_store(reg, 0, 0);
-	reg |= CR0_LOW_ADDRESS_PROTECTION;
-	reg |= CR0_EMERGENCY_SIGNAL_SUBMASK;
-	reg |= CR0_EXTERNAL_CALL_SUBMASK;
-	__ctl_load(reg, 0, 0);
+	__ctl_set_bit(0, 28);
 }
 
 static inline void setup_access_registers(void)
@@ -314,7 +308,7 @@ void __init startup_init(void)
 	save_vector_registers();
 	setup_topology();
 	sclp_early_detect();
-	setup_control_registers();
+	setup_low_address_protection();
 	setup_access_registers();
 	lockdep_on();
 }
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index a4edb7ea66ea7..c63be2efd6895 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -1013,12 +1013,12 @@ void __init smp_fill_possible_mask(void)
 
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
-	/* request the 0x1201 emergency signal external interrupt */
 	if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 		panic("Couldn't request external interrupt 0x1201");
-	/* request the 0x1202 external call external interrupt */
+	ctl_set_bit(0, 14);
 	if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 		panic("Couldn't request external interrupt 0x1202");
+	ctl_set_bit(0, 13);
 }
 
 void __init smp_prepare_boot_cpu(void)




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